Communications systems transmit video, voice, and data signals comprised in a transport stream, such as an MPEG (Motions Picture Entertainment Group) stream. The video, voice, and data signals are packaged in packets each having a packet identification number (PID) and then transmitted throughout the system according to header information. At times, the transport stream may include duplicate packets. The MPEG specification states that in transport streams, duplicate packets may be sent as two, and only two, consecutive transport stream packets of the same PID. In the duplicate packets, each byte of the original packet shall be duplicated, with the exception that in a program clock reference (PCR) field, if present, a valid value shall be encoded.
If the duplicate packet is generated at the time the transport packet stream is generated, creating the valid PCR value for the duplicate packet is a simple process. More specifically, when a duplicate packet is duplicated a clock reference is taken immediately from a system clock. If, however, the duplicate packet is added to the stream at some point during the transmission process, there is no specified scheme for generating a valid PCR value since the system clock is not available. What is needed, therefore, is a method and system to generate a valid PCR value when a packet in the transport stream is duplicated during the transmission process.